The upgrade of the ALICE TPC with GEMs and continuous readout

TL;DR

The paper details the design, construction, and commissioning of an upgraded ALICE TPC with GEM detectors and continuous readout electronics to handle higher interaction rates at CERN LHC, completed in 2020.

Contribution

It introduces a novel TPC upgrade with GEM technology and continuous electronics, including quality control and integration procedures.

Findings

Successful implementation of GEM-based readout chambers

Enhanced data acquisition capabilities for high interaction rates

Complete upgrade process completed in 2020

Abstract

The upgrade of the ALICE TPC will allow the experiment to cope with the high interaction rates foreseen for the forthcoming Run 3 and Run 4 at the CERN LHC. In this article, we describe the design of new readout chambers and front-end electronics, which are driven by the goals of the experiment. Gas Electron Multiplier (GEM) detectors arranged in stacks containing four GEMs each, and continuous readout electronics based on the SAMPA chip, an ALICE development, are replacing the previous elements. The construction of these new elements, together with their associated quality control procedures, is explained in detail. Finally, the readout chamber and front-end electronics cards replacement, together with the commissioning of the detector prior to installation in the experimental cavern, are presented. After a nine-year period of R&D, construction, and assembly, the upgrade of the TPC was completed in 2020.